Marine Pollution Bulletin

Contents lists available atScienceDirect

Marine Pollution Bulletin

journal homepage:www.elsevier.com/locate/marpolbul

E ffects of sub-seabed CO 2 leakage: Short- and medium-term responses of benthic macrofaunal assemblages

T. Amaro

, I. Bertocci

, A.M. Queiros

, E. Rastelli

, G. Borgersen

, M. Brkljacic

, J. Nunes

, K. Sorensen

, R. Danovaro

, S. Widdicombe

aHellenic Center for Marine Research (HCMR), 710 03 Heraklion, Crete, Greece

bNorwegian Institute for Water Research, Oslo, Norway

cStazione Zoologica Anton Dohrn, Villa Comunale, Naples, Italy

dPlymouth Marine Laboratory, Prospect Place, West Hoe, PL1 3DH, Plymouth, UK

eDepartment of Life and Environmental Sciences, Polytechnic University of Marche, Ancona, Italy

A R T I C L E I N F O

Keywords:

CCS CO2 Macrobenthos Impacts

A B S T R A C T

The continued rise in atmospheric carbon dioxide (CO₂) levels is driving climate change and temperature shifts at a global scale. CO2Capture and Storage (CCS) technologies have been suggested as a feasible option for reducing CO2emissions and mitigating their effects. However, before CCS can be employed at an industrial scale, any environmental risks associated with this activity should be identified and quantified. Significant leakage of CO2from CCS reservoirs and pipelines is considered to be unlikely, however direct and/or indirect effects of CO2

leakage on marine life and ecosystem functioning must be assessed, with particular consideration given to spatial (e.g. distance from the source) and temporal (e.g. duration) scales at which leakage impacts could occur. In the current mesocosm experiment we tested the potential effects of CO2leakage on macrobenthic assemblages by exposing infaunal sediment communities to different levels of CO2concentration (400, 1000, 2000, 10,000 and 20,000 ppm CO₂), simulating a gradient of distance from a hypothetic leakage, over short-term (a few weeks) and medium-term (several months). A significant impact on community structure, abundance and species richness of macrofauna was observed in the short-term exposure. Individual taxa showed idiosyncratic responses to acidification. We conclude that the main impact of CO2leakage on macrofaunal assemblages occurs almost exclusively at the higher CO2concentration and over short time periods, tending to fade and disappear at increasing distance and exposure time. Although under the cautious perspective required by the possible con- text-dependency of the presentfindings, this study contributes to the cost-benefit analysis (environmental risk versus the achievement of the intended objectives) of CCS strategies.

1. Introduction

The accelerating rise in atmospheric carbon dioxide (CO2) levels (IPCC, 2013) is causing ocean warming and acidification at un- precedented rates, posing critical threats to single species, habitats, oceanic regions and overall global ecosystem functioning (Caldeira and Wickett, 2003;Feely et al., 2004;Hale et al., 2011;Mora et al., 2013, Cerrano et al., 2013;Meadows et al., 2015;Gattuso et al., 2015). As a direct consequence, it is urgently needed to identify suitable options for reducing/mitigating CO2 emissions (McCormack et al., 2016). One particularly promising technology involves capturing CO2from point source effluents (mostly, energy generation plants), then transporting it as a supercritical liquid to be stored in deep porous geological rock formations, such as saline aquifers or existing hydrocarbon reservoirs

(Gibbins et al. 2006;Holloway 2007). This process is defined as CO2

Capture and Storage (CCS). In Europe and North America the technical feasibility of CCS approaches has been already demonstrated. For ex- ample, at the Sleipner West gasfield in the Norwegian sector of the North Sea, CCS has been operational since 2000 with approximately 1 million tons of CO2 pumped into the storage reservoir every year (Paulley et al., 2012,Jones et al., 2015). However, as with almost any other human activity, this technology is not risk-free in terms of posing potential environmental hazards (reviewed by Damen et al. 2006).

Before industrial scale CCS activities become widely accepted and im- plemented these risks need to be identified and quantified. Perhaps the greatest environmental risk associated with CCS is that of CO2leaking into the marine environment either during transport, sequestration or from the geological storage reservoir itself. Whilst current evidence

https://doi.org/10.1016/j.marpolbul.2018.01.068

Received 18 January 2017; Received in revised form 30 January 2018; Accepted 31 January 2018

⁎Corresponding author at: Hellenic Center for Marine Research (HCMR), 710 03 Heraklion, Crete, Greece.

E-mail address:[email protected](T. Amaro).

Marine Pollution Bulletin 128 (2018) 519–526

0025-326X/ © 2018 Published by Elsevier Ltd.

T